******************************************************************************* Revised: June 02, 2025 Mars 499 / 4 PHYSICAL DATA (updated 2025-Jun-02): Vol. mean radius (km) = 3389.92+-0.04 Density (g/cm^3) = 3.933(5+-4) Mass x10^23 (kg) = 6.4171 Flattening, f = 1/169.779 Volume (x10^10 km^3) = 16.318 Equatorial radius (km)= 3396.19 Sidereal rot. period = 24.622962 hr Sid. rot. rate, rad/s = 0.0000708822 Mean solar day (sol) = 88775.24415 s Polar gravity m/s^2 = 3.758 Core radius (km) = ~1700 Equ. gravity m/s^2 = 3.71 Geometric Albedo = 0.150 GM (km^3/s^2) = 42828.375662 Mass ratio (Sun/Mars) = 3098703.59 GM 1-sigma (km^3/s^2) = +- 0.00028 Mass of atmosphere, kg= ~ 2.5 x 10^16 Mean temperature (K) = 210 Atmos. pressure (bar) = 0.0056 Obliquity to orbit = 25.19 deg Max. angular diam. = 17.9" Mean sidereal orb per = 1.88081578 y Visual mag. V(1,0) = -1.52 Mean sidereal orb per = 686.98 d Orbital speed, km/s = 24.13 Hill's sphere rad. Rp = 319.8 Escape speed, km/s = 5.027 Perihelion Aphelion Mean Solar Constant (W/m^2) 717 493 589 Maximum Planetary IR (W/m^2) 470 315 390 Minimum Planetary IR (W/m^2) 30 30 30 ******************************************************************************* ******************************************************************************* Ephemeris / WWW_USER Fri Oct 16 12:38:40 2026 Pasadena, USA / Horizons ******************************************************************************* Target body name: Mars (499) {source: mar099} Center body name: Earth (399) {source: DE441} Center-site name: GEOCENTRIC ******************************************************************************* Start time : A.D. 2022-Jan-01 10:00:00.0000 UT Stop time : A.D. 2022-Jan-02 00:00:00.0000 UT Step-size : 60 minutes ******************************************************************************* Target pole/equ : IAU_MARS {West-longitude positive} Target radii : 3396.19, 3396.19, 3376.2 km {Equator_a, b, pole_c} Center geodetic : 0.0, 0.0, -6378.137 {E-lon(deg),Lat(deg),Alt(km)} Center cylindric: 0.0, 0.0, 0.0 {E-lon(deg),Dxy(km),Dz(km)} Center pole/equ : ITRF93 {East-longitude positive} Center radii : 6378.137, 6378.137, 6356.752 km {Equator_a, b, pole_c} Target primary : Sun Vis. interferer : MOON (R_eq= 1737.400) km {source: DE441} Rel. light bend : Sun {source: DE441} Rel. lght bnd GM: 1.3271E+11 km^3/s^2 Atmos refraction: NO (AIRLESS) RA format : HMS Time format : CAL Calendar mode : Mixed Julian/Gregorian EOP file : eop.261015.p270111 EOP coverage : DATA-BASED 1962-JAN-20 TO 2026-OCT-15. PREDICTS-> 2027-JAN-10 Units conversion: 1 au= 149597870.700 km, c= 299792.458 km/s, 1 day= 86400.0 s Table cut-offs 1: Elevation (-90.0deg=NO ),Airmass (>38.000=NO), Daylight (NO ) Table cut-offs 2: Solar elongation ( 0.0,180.0=NO ),Local Hour Angle( 0.0=NO ) Table cut-offs 3: RA/DEC angular rate ( 0.0=NO ) ******************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************** Date__(UT)__HR:MN R.A._____(ICRF)_____DEC R.A.__(a-apparent)__DEC dRA*cosD d(DEC)/dt Azi____(a-app)___Elev dAZ*cosE d(ELV)/dt X_(sat-primary)_Y SatPANG L_Ap_Sid_Time a-mass mag_ex APmag S-brt Illu% Def_illu ang-sep/v Ang-diam ObsSub-LON ObsSub-LAT SunSub-LON SunSub-LAT SN.ang SN.dist NP.ang NP.dist hEcl-Lon hEcl-Lat r rdot delta deldot 1-way_down_LT VmagSn VmagOb S-O-T /r S-T-O T-O-M/MN_Illu% O-P-T PsAng PsAMV PlAng Cnst TDB-UT ObsEcLon ObsEcLat N.Pole-RA N.Pole-DC GlxLon GlxLat L_Ap_SOL_Time 399_ins_LT RA_3sigma DEC_3sigma SMAA_3sig SMIA_3sig Theta Area_3sig POS_3sigma RNG_3sigma RNGRT_3sig DOP_S_3sig DOP_X_3sig RT_delay_3sig Tru_Anom L_Ap_Hour_Ang phi PAB-LON PAB-LAT App_Lon_Sun RA_(ICRF-a-apparnt)_DEC I_dRA*cosD I_d(DEC)/dt Sky_motion Sky_mot_PA RelVel-ANG Lun_Sky_Brt sky_SNR UT1-UTC ******************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************** $$SOE 2022-Jan-01 10:00 16 46 37.58 -22 30 11.3 16 47 54.44 -22 32 28.6 105.6449 -14.7665 n.a. n.a. n.a. n.a. -99209.4 1600.652 264.996 n.a. n.a. n.a. 1.579 4.304 97.75545 0.0899 99211.33/* 4.004037 358.745723 4.546871 14.449284 12.102597 96.81 0.59 33.4583 1.984 235.8690 -0.2054 1.536114010133 -2.2264750 2.33896443262049 -9.1067796 19.45257402 23.9325777 51.0847555 27.5587 /L 17.2277 8.541/ 2.8123 135.2136 276.929 279.012 -0.60983 Oph 69.183903 253.3953914 -0.1365775 317.65726 52.87271 357.659530 14.567662 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.6355 n.a. 17.2328 244.4808 -0.1714 150.8571593 16 46 36.26 -22 30 08.9 105.6127 -14.9950 1.7778649 97.956939 -10.27403 n.a. n.a. -0.11046 2022-Jan-01 11:00 16 46 45.21 -22 30 26.2 16 48 02.06 -22 32 43.4 105.6519 -14.7449 n.a. n.a. n.a. n.a. -99259.1 1573.318 264.977 n.a. n.a. n.a. 1.574 4.299 97.75332 0.0900 99257.61/* 4.004412 13.339839 4.533963 29.050004 12.094378 96.80 0.59 33.4482 1.984 235.8904 -0.2061 1.536060427639 -2.2266269 2.33874525769586 -9.1091327 19.45075120 23.9334194 51.0823752 27.5716 /L 17.2359 9.141/ 2.6470 135.1925 276.917 279.000 -0.61025 Oph 69.183904 253.4250251 -0.1370367 317.65726 52.87271 357.674865 14.542015 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.6569 n.a. 17.2410 244.5063 -0.1720 150.8785490 16 46 43.88 -22 30 23.9 105.6198 -14.9735 1.7779309 97.944923 -10.27719 n.a. n.a. -0.11046 2022-Jan-01 12:00 16 46 52.83 -22 30 41.2 16 48 09.69 -22 32 58.1 105.6589 -14.7232 n.a. n.a. n.a. n.a. -99308.7 1545.959 264.958 n.a. n.a. n.a. 1.554 4.280 97.75118 0.0901 99303.88/* 4.004788 27.933955 4.521053 43.650724 12.086158 96.78 0.59 33.4381 1.984 235.9117 -0.2067 1.536006841493 -2.2267785 2.33852602616847 -9.1114841 19.44892790 23.9342611 51.0799918 27.5844 /L 17.2442 9.741/ 2.4867 135.1714 276.904 278.988 -0.61066 Oph 69.183906 253.4546599 -0.1374960 317.65726 52.87271 357.690197 14.516365 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.6783 n.a. 17.2493 244.5318 -0.1726 150.8999402 16 46 51.51 -22 30 38.9 105.6268 -14.9519 1.7779968 97.932904 -10.28036 n.a. n.a. -0.11045 2022-Jan-01 13:00 16 47 00.45 -22 30 56.1 16 48 17.32 -22 33 12.8 105.6659 -14.7016 n.a. n.a. n.a. n.a. -99358.4 1518.573 264.939 n.a. n.a. n.a. 1.548 4.274 97.74905 0.0902 99350.15/* 4.005163 42.528071 4.508142 58.251444 12.077936 96.77 0.59 33.4280 1.985 235.9331 -0.2074 1.535953251702 -2.2269298 2.33830673808007 -9.1138338 19.44710414 23.9351029 51.0776053 27.5973 /L 17.2524 10.3/ 2.3314 135.1503 276.891 278.975 -0.61108 Oph 69.183907 253.4842958 -0.1379553 317.65726 52.87271 357.705527 14.490713 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.6997 n.a. 17.2575 244.5573 -0.1732 150.9213329 16 46 59.13 -22 30 53.8 105.6338 -14.9304 1.7780626 97.920882 -10.28352 n.a. n.a. -0.11045 2022-Jan-01 14:00 16 47 08.08 -22 31 11.1 16 48 24.95 -22 33 27.5 105.6729 -14.6800 n.a. n.a. n.a. n.a. -99408.0 1491.161 264.921 n.a. n.a. n.a. 1.530 4.256 97.74691 0.0902 99396.41/* 4.005539 57.122187 4.495230 72.852164 12.069711 96.76 0.59 33.4179 1.985 235.9545 -0.2081 1.535899658272 -2.2270808 2.33808739347294 -9.1161817 19.44527991 23.9359448 51.0752157 27.6101 /L 17.2607 10.9/ 2.1812 135.1292 276.878 278.963 -0.61149 Oph 69.183908 253.5139328 -0.1384147 317.65726 52.87271 357.720853 14.465060 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.7210 n.a. 17.2658 244.5828 -0.1738 150.9427271 16 47 06.75 -22 31 08.7 105.6409 -14.9088 1.7781284 97.908856 -10.28668 n.a. n.a. -0.11044 2022-Jan-01 15:00 16 47 15.70 -22 31 26.0 16 48 32.58 -22 33 42.2 105.6799 -14.6583 n.a. n.a. n.a. n.a. -99457.7 1463.723 264.902 n.a. n.a. n.a. 1.519 4.245 97.74477 0.0903 99442.68/* 4.005915 71.716303 4.482316 87.452884 12.061485 96.74 0.59 33.4078 1.985 235.9759 -0.2088 1.535846061211 -2.2272315 2.33786799239015 -9.1185278 19.44345520 23.9367867 51.0728230 27.6230 /L 17.2689 11.5/ 2.0360 135.1081 276.865 278.951 -0.61191 Oph 69.183909 253.5435709 -0.1388742 317.65726 52.87271 357.736176 14.439404 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.7424 n.a. 17.2740 244.6083 -0.1743 150.9641229 16 47 14.38 -22 31 23.6 105.6479 -14.8872 1.7781942 97.896828 -10.28985 n.a. n.a. -0.11043 2022-Jan-01 16:00 16 47 23.33 -22 31 40.8 16 48 40.21 -22 33 56.9 105.6869 -14.6367 n.a. n.a. n.a. n.a. -99507.3 1436.259 264.883 n.a. n.a. n.a. 1.495 4.222 97.74263 0.0904 99488.93/* 4.006291 86.310419 4.469401 102.053603 12.053256 96.73 0.60 33.3976 1.985 235.9973 -0.2095 1.535792460527 -2.2273819 2.33764853487552 -9.1208720 19.44163003 23.9376287 51.0704271 27.6358 /L 17.2772 12.1/ 1.8959 135.0870 276.852 278.939 -0.61232 Oph 69.183910 253.5732101 -0.1393338 317.65726 52.87271 357.751496 14.413746 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.7638 n.a. 17.2823 244.6339 -0.1749 150.9855201 16 47 22.00 -22 31 38.5 105.6549 -14.8656 1.7782599 97.884796 -10.29301 n.a. n.a. -0.11043 2022-Jan-01 17:00 16 47 30.95 -22 31 55.7 16 48 47.84 -22 34 11.5 105.6939 -14.6150 n.a. n.a. n.a. n.a. -99557.0 1408.768 264.864 n.a. n.a. n.a. 1.479 4.206 97.74050 0.0905 99535.19/* 4.006667 100.904535 4.456485 116.654323 12.045026 96.72 0.60 33.3875 1.986 236.0187 -0.2102 1.535738856227 -2.2275320 2.33742902097344 -9.1232144 19.43980439 23.9384709 51.0680282 27.6487 /L 17.2854 12.7/ 1.7610 135.0659 276.840 278.926 -0.61274 Oph 69.183912 253.6028505 -0.1397934 317.65726 52.87271 357.766813 14.388087 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.7852 n.a. 17.2905 244.6594 -0.1755 151.0069188 16 47 29.63 -22 31 53.4 105.6619 -14.8440 1.7783255 97.872761 -10.29617 n.a. n.a. -0.11042 2022-Jan-01 18:00 16 47 38.58 -22 32 10.5 16 48 55.47 -22 34 26.1 105.7008 -14.5934 n.a. n.a. n.a. n.a. -99606.6 1381.252 264.845 n.a. n.a. n.a. 1.478 4.205 97.73836 0.0906 99581.44/* 4.007044 115.498651 4.443567 131.255043 12.036793 96.71 0.60 33.3773 1.986 236.0401 -0.2109 1.535685248318 -2.2276818 2.33720945072851 -9.1255550 19.43797828 23.9393131 51.0656261 27.6615 /L 17.2937 13.3/ 1.6311 135.0448 276.827 278.914 -0.61315 Oph 69.183913 253.6324919 -0.1402531 317.65726 52.87271 357.782126 14.362425 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.8066 n.a. 17.2988 244.6849 -0.1761 151.0283190 16 47 37.26 -22 32 08.2 105.6689 -14.8224 1.7783911 97.860722 -10.29932 n.a. n.a. -0.11041 2022-Jan-01 19:00 16 47 46.21 -22 32 25.3 16 49 03.11 -22 34 40.7 105.7078 -14.5717 n.a. n.a. n.a. n.a. -99656.2 1353.709 264.827 n.a. n.a. n.a. 1.491 4.218 97.73622 0.0907 99627.69/* 4.007420 130.092767 4.430648 145.855762 12.028559 96.69 0.60 33.3672 1.986 236.0615 -0.2115 1.535631636808 -2.2278313 2.33698982418537 -9.1278937 19.43615170 23.9401554 51.0632209 27.6744 /L 17.3019 14.0/ 1.5065 135.0237 276.814 278.902 -0.61357 Oph 69.183914 253.6621345 -0.1407128 317.65726 52.87271 357.797437 14.336762 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.8280 n.a. 17.3070 244.7104 -0.1767 151.0497207 16 47 44.88 -22 32 23.0 105.6759 -14.8008 1.7784567 97.848681 -10.30248 n.a. n.a. -0.11040 2022-Jan-01 20:00 16 47 53.84 -22 32 40.1 16 49 10.74 -22 34 55.2 105.7147 -14.5500 n.a. n.a. n.a. n.a. -99705.8 1326.140 264.808 n.a. n.a. n.a. 1.495 4.222 97.73407 0.0908 99673.93/* 4.007797 144.686883 4.417728 160.456481 12.020322 96.68 0.60 33.3570 1.986 236.0828 -0.2122 1.535578021704 -2.2279805 2.33677014138865 -9.1302305 19.43432465 23.9409978 51.0608127 27.6872 /L 17.3101 14.6/ 1.3869 135.0026 276.801 278.889 -0.61398 Oph 69.183915 253.6917781 -0.1411727 317.65726 52.87271 357.812745 14.311096 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.8494 n.a. 17.3153 244.7359 -0.1772 151.0711238 16 47 52.51 -22 32 37.8 105.6829 -14.7792 1.7785222 97.836636 -10.30564 n.a. n.a. -0.11040 2022-Jan-01 21:00 16 48 01.46 -22 32 54.9 16 49 18.38 -22 35 09.8 105.7217 -14.5283 n.a. n.a. n.a. n.a. -99755.5 1298.546 264.789 n.a. n.a. n.a. 1.498 4.226 97.73193 0.0909 99720.17/* 4.008174 159.280999 4.404806 175.057201 12.012084 96.67 0.60 33.3468 1.986 236.1042 -0.2129 1.535524403012 -2.2281294 2.33655040238322 -9.1325654 19.43249714 23.9418403 51.0584013 27.7000 /L 17.3184 15.2/ 1.2726 134.9816 276.788 278.877 -0.61440 Oph 69.183917 253.7214228 -0.1416325 317.65726 52.87271 357.828050 14.285429 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.8708 n.a. 17.3235 244.7614 -0.1778 151.0925285 16 48 00.14 -22 32 52.6 105.6899 -14.7576 1.7785877 97.824589 -10.30879 n.a. n.a. -0.11039 2022-Jan-01 22:00 16 48 09.09 -22 33 09.6 16 49 26.01 -22 35 24.3 105.7286 -14.5066 n.a. n.a. n.a. n.a. -99805.1 1270.925 264.770 n.a. n.a. n.a. 1.502 4.229 97.72979 0.0910 99766.41/* 4.008551 173.875115 4.391882 189.657920 12.003843 96.65 0.60 33.3367 1.987 236.1256 -0.2136 1.535470780739 -2.2282780 2.33633060721462 -9.1348985 19.43066916 23.9426829 51.0559868 27.7129 /L 17.3266 15.8/ 1.1635 134.9605 276.775 278.865 -0.61481 Oph 69.183918 253.7510687 -0.1420925 317.65726 52.87271 357.843352 14.259759 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.8922 n.a. 17.3318 244.7869 -0.1784 151.1139347 16 48 07.77 -22 33 07.3 105.6969 -14.7359 1.7786531 97.812538 -10.31194 n.a. n.a. -0.11038 2022-Jan-01 23:00 16 48 16.72 -22 33 24.3 16 49 33.65 -22 35 38.8 105.7356 -14.4849 n.a. n.a. n.a. n.a. -99854.7 1243.278 264.752 n.a. n.a. n.a. 1.508 4.236 97.72764 0.0911 99812.64/* 4.008928 188.469231 4.378958 204.258639 11.995600 96.64 0.60 33.3265 1.987 236.1470 -0.2143 1.535417154894 -2.2284263 2.33611075592919 -9.1372296 19.42884071 23.9435255 51.0535691 27.7257 /L 17.3349 16.4/ 1.0595 134.9394 276.763 278.852 -0.61522 Oph 69.183919 253.7807156 -0.1425525 317.65726 52.87271 357.858651 14.234088 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.9136 n.a. 17.3400 244.8125 -0.1790 151.1353424 16 48 15.40 -22 33 22.1 105.7039 -14.7143 1.7787184 97.800484 -10.31509 n.a. n.a. -0.11037 2022-Jan-02 00:00 16 48 24.36 -22 33 39.0 16 49 41.28 -22 35 53.3 105.7425 -14.4632 n.a. n.a. n.a. n.a. -99904.3 1215.606 264.733 n.a. n.a. n.a. 1.527 4.255 97.72550 0.0912 99858.87/* 4.009306 203.063347 4.366032 218.859358 11.987355 96.63 0.60 33.3163 1.987 236.1684 -0.2150 1.535363525482 -2.2285743 2.33589084857395 -9.1395587 19.42701180 23.9443682 51.0511484 27.7386 /L 17.3431 17.0/ 0.9608 134.9183 276.750 278.840 -0.61564 Oph 69.183920 253.8103637 -0.1430126 317.65726 52.87271 357.873947 14.208415 n.a. 0.000000 n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. n.a. 259.9350 n.a. 17.3483 244.8380 -0.1796 151.1567516 16 48 23.03 -22 33 36.8 105.7108 -14.6926 1.7787837 97.788427 -10.31825 n.a. n.a. -0.11036 $$EOE ******************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************** Column meaning: TIME Times PRIOR to 1962 are UT1, a mean-solar time closely related to the prior but now-deprecated GMT. Times AFTER 1962 are in UTC, the current civil or "wall-clock" time-scale. UTC is kept within 0.9 seconds of UT1 using integer leap-seconds for 1972 and later years. Conversion from the internal Barycentric Dynamical Time (TDB) of solar system dynamics to the non-uniform civil UT time-scale requested for output has not been determined for UTC times after the next July or January 1st. Therefore, the last known leap-second is used as a constant over future intervals. Time tags refer to the UT time-scale conversion from TDB on Earth regardless of observer location within the solar system, although clock rates may differ due to the local gravity field and no analog to "UT" may be defined for that location. Any 'b' symbol in the 1st-column denotes a B.C. date. First-column blank (" ") denotes an A.D. date. CALENDAR SYSTEM Mixed calendar mode was active such that calendar dates after AD 1582-Oct-15 (if any) are in the modern Gregorian system. Dates prior to 1582-Oct-5 (if any) are in the Julian calendar system, which is automatically extended for dates prior to its adoption on 45-Jan-1 BC. The Julian calendar is useful for matching historical dates. The Gregorian calendar more accurately corresponds to the Earth's orbital motion and seasons. A "Gregorian-only" calendar mode is available if such physical events are the primary interest. NOTE: "n.a." in output means quantity "not available" at the print-time. 'R.A._____(ICRF)_____DEC' = Astrometric right ascension and declination of the target center with respect to the observing site (coordinate origin) in the reference frame of the planetary ephemeris (ICRF). Compensated for down-leg light-time delay aberration. Units: RA in hours-minutes-seconds of time, HH MM SS.ff{ffff} DEC in degrees-minutes-seconds of arc, sDD MN SC.f{ffff} 'R.A.__(a-apparent)__DEC' = Airless apparent right ascension and declination of the target center with respect to an instantaneous reference frame defined by the Earth equator of-date (z-axis) and meridian containing the Earth equinox of-date (x-axis, EOP-corrected IAU76/80). Compensated for down-leg light-time delay, gravitational deflection of light, stellar aberration, precession & nutation. Note: equinox (RA origin) is offset -53 mas from the of-date frame defined by the IAU06/00a P & N system. Units: RA in hours-minutes-seconds of time, HH MM SS.ff{ffff} DEC in degrees-minutes-seconds of arc, sDD MN SC.f{ffff} 'dRA*cosD d(DEC)/dt' = The angular rate of change in apparent RA and DEC of the target. This is with respect to the non-inertial IAU76/80 Earth true equator and equinox of-date reference frame. d(RA)/dt is multiplied by the cosine of declination to provide a linear rate in the plane-of-sky. Units: ARCSECONDS PER HOUR 'Azi____(a-app)___Elev' = Airless apparent azimuth and elevation of target center. Compensated for light-time, the gravitational deflection of light, stellar aberration, precession and nutation. Azimuth is measured clockwise from north: North(0) -> East(90) -> South(180) -> West(270) -> North (360) Elevation angle is with respect to a plane perpendicular to the reference surface local zenith direction. TOPOCENTRIC ONLY. Units: DEGREES 'dAZ*cosE d(ELV)/dt' = The rate of change of target center apparent azimuth and elevation (airless). d(AZ)/dt is multiplied by the cosine of the elevation angle. TOPOCENTRIC ONLY. Units: ARCSECOND PER MINUTE 'X_(sat-primary)_Y SatPANG' = Satellite apparent differential coordinates in the plane-of-sky with respect to the primary body along with the satellite position angle. Differential coordinates are defined in RA as: X= ((RA_sat - RA_primary) * cosine(DEC_primary)) ... and in DEC as: Y= (DEC_sat - DEC_primary) Non-lunar satellites only. "SatPANG" is the counter-clockwise (CCW) position angle from the reference-frame of-date north-pole to a line from the primary center to the satellite center. Units: ARCSECONDS (X & Y), DEGREES (pos, angle) 'L_Ap_Sid_Time' = Local Apparent Sidereal Time. The angle measured westward in the body true-equator of-date plane from the meridian containing the body-fixed observer to the meridian containing the true Earth equinox (defined by intersection of the true Earth equator of date with the ecliptic of date). TOPOCENTRIC ONLY. Units: HH MM SS.ffff (hours-minutes-seconds of time) 'a-mass mag_ex' = RELATIVE optical airmass and visual magnitude extinction. Airmass is the ratio between the absolute optical airmass for the targets' refracted CENTER point to the absolute optical airmass at zenith. Also output is the estimated visual magnitude extinction due to the atmosphere, as seen by the observer. AVAILABLE ONLY FOR TOPOCENTRIC EARTH SITES WHEN THE TARGET IS ABOVE THE HORIZON. Units: none (airmass) and magnitudes (extinction). 'APmag S-brt' = The targets' approximate apparent visual magnitude and surface brightness. For planets and natural satellites, output is restricted to solar phase angles covered by observational data. Outside the observed phase angle range, "n.a." may be output to avoid extrapolation beyond the limit of model validity. For Earth-based observers, the estimated dimming due to atmospheric absorption (extinction) is available as a separate, requestable quantity. Surface brightness is the average airless visual magnitude of a square-arcsecond of the illuminated portion of the apparent disk. It is computed only if the target radius is known. Units: MAGNITUDES & MAGNITUDES PER SQUARE ARCSECOND 'Illu%' = Fraction of the target objects' assumed circular disk illuminated by Sun (phase), as seen by the observer. Units: PERCENT 'Def_illu' = Defect of illumination. The maximum angular width of the target body's assumed circular disk diameter NOT illuminated by the Sun. Units: ARCSECONDS 'ang-sep/v' = The angular separation between the center of the target object and the center of the (remote) primary body it revolves around, as seen by the observer, with target visibility code. Visibility codes (refers to limb-to-limb): /t = Transiting primary body disk /O = Occulted by primary body disk /p = Partial umbral eclipse /P = Occulted partial umbral eclipse /u = Total umbral eclipse /U = Occulted total umbral eclipse /- = Target is the primary body /* = None of above ("free and clear") The radius of both primary and target body is taken to be the equatorial value (maximum, given a triaxial shape). Atmospheric effects and oblateness aspect are NOT currently considered. Light-time is considered. Units: ARCSECONDS and visibility code 'Ang-diam' = The equatorial angular width of the target body full disk, if it were fully illuminated and visible to the observer. If the target body diameter is unknown "n.a." is output. Units: ARCSECONDS 'ObsSub-LON ObsSub-LAT' = Apparent planetodetic longitude and latitude of the center of the target disc seen by the OBSERVER at print-time. This is NOT exactly the same as the "nearest" sub-point for a non-spherical target shape (since the center of the disc might not be the point closest to the observer), but is generally very close if not a very irregular body shape. Down-leg light travel-time from target to observer is taken into account. Latitude is the angle between the equatorial plane and the line perpendicular to the reference ellipsoid of the body, so includes body oblateness. The reference ellipsoid is an oblate spheroid with a single flatness coefficient in which the y-axis body radius is taken to be the same value as the x-axis radius. Positive longitude is to the WEST for this target. Cartographic system is given in the header. Units: DEGREES DEGREES 'SunSub-LON SunSub-LAT' = Apparent sub-solar longitude and latitude of the Sun on the target. The apparent planetodetic longitude and latitude of the center of the target disc as seen from the Sun, as seen by the observer at print-time. This is NOT exactly the same as the "sub-solar" (nearest) point for a non-spherical target shape (since the center of the disc seen from the Sun might not be the closest point to the Sun), but is very close if not a highly irregular body shape. Light travel-time from Sun to target and from target to observer is taken into account. Latitude is the angle between the equatorial plane and the line perpendicular to the reference ellipsoid of the body. The reference ellipsoid is an oblate spheroid with a single flatness coefficient in which the y-axis body radius is taken to be the same value as the x-axis radius. Positive longitude is to the WEST for this target. Cartographic system is given in the header. Units: DEGREES DEGREES 'SN.ang SN.dist' = Targets' apparent sub-solar point position angle (counter-clockwise with respect to the direction of the true-of-date reference-frame north-pole) and its angular distance from the sub-observer point (center of disk) at print time. A negative distance indicates the sub-solar point is on the hidden hemisphere. Units: DEGREES and ARCSECONDS 'NP.ang NP.dist' = Targets' apparent north-pole position angle (counter-clockwise with respect to the direction of the true-of-date reference-frame north-pole) and its angular distance from the sub-observer point (center of disk) at observation time. A negative distance indicates the planets' north-pole is on the hidden hemisphere. Units: DEGREES and ARCSECONDS 'hEcl-Lon hEcl-Lat' = Geometric heliocentric J2000 ecliptic longitude and latitude of target center at the instant light leaves it to be observed at print time (print time minus down-leg light-time). Units: DEGREES 'r rdot' = The Sun's apparent range ("r", light-time aberrated) and range-rate ("rdot") relative to the target center, as seen by the observer. A positive "rdot" means the target center was moving away from the Sun, negative means moving toward the Sun. Units: AU and KM/S 'delta deldot' = Apparent range ("delta", light-time aberrated) and range-rate ("delta-dot") of the target center relative to the observer. A positive "deldot" means the target center is moving away from the observer, negative indicates movement toward the observer. Units: AU and KM/S '1-way_down_LT' = 1-way down-leg light-time from target center to observer. The elapsed time since light (observed at print-time) would have left or reflected off a point at the center of the target. Units: MINUTES 'VmagSn VmagOb' = Magnitude of target centers' velocity with respect to the Sun ("VmagSn") and the observer ("VmagOb") at the time light left the target center to be observed (print time minus down-leg light-time). These are absolute values of the velocity vectors (total speeds) and do NOT indicate direction of motion. Units: KM/S 'S-O-T /r' = Sun-Observer-Target apparent SOLAR ELONGATION ANGLE seen from the observers' location at print-time. The '/r' column provides a code indicating the targets' apparent position relative to the Sun in the observers' sky, as described below: Case A: For an observing location on the surface of a rotating body, that body rotational sense is considered: /T indicates target TRAILS Sun (evening sky: rises and sets AFTER Sun) /L indicates target LEADS Sun (morning sky: rises and sets BEFORE Sun) Case B: For an observing point that does not have a rotational model (such as a spacecraft), the "leading" and "trailing" condition is defined by the observers' heliocentric ORBITAL motion: * If continuing in the observers' current direction of heliocentric motion would encounter the targets' apparent longitude first, followed by the Sun's, the target LEADS the Sun as seen by the observer. * If the Sun's apparent longitude would be encountered first, followed by the targets', the target TRAILS the Sun. Two other codes can be output: /* indicates observer is Sun-centered (undefined) /? Target is aligned with Sun center (no lead or trail) The S-O-T solar elongation angle is numerically the minimum separation angle of the Sun and target in the sky in any direction. It does NOT indicate the amount of separation in the leading or trailing directions, which would be defined along the equator of a spherical coordinate system. Units: DEGREES 'S-T-O' = The Sun-Target-Observer angle; the interior vertex angle at target center formed by a vector from the target to the apparent center of the Sun (at reflection time on the target) and the apparent vector from target to the observer at print-time. Slightly different from true PHASE ANGLE (requestable separately) at the few arcsecond level in that it includes stellar aberration on the down-leg from target to observer. Units: DEGREES 'T-O-M/MN_Illu%' = Target-Observer-Moon LUNAR ELONGATION angle and illuminated percentage. The apparent lunar elongation angle between target body center and Moon center, seen from the observing site, along with fraction of the lunar disk illuminated by the Sun. A negative lunar elongation angle indicates the target center is behind the Moon. Units: DEGREES & PERCENT 'O-P-T' = Observer-Primary-Target angle; apparent angle between a target satellite, its primarys' center and an observer at print time. Interior vertex angle at the primary. Units: DEGREES 'PsAng PsAMV' = The position angles of the extended Sun-to-target radius vector ("PsAng") and the negative of the targets' heliocentric velocity vector ("PsAMV"), as seen in the observers' plane-of-sky, measured counter-clockwise (east) from reference-frame north-pole. Primarily intended for ACTIVE COMETS, "PsAng" is an indicator of the comets' gas-tail orientation in the sky (being in the anti-sunward direction) while "PsAMV" is an indicator of dust-tail orientation. Units: DEGREES 'PlAng' = Angle between observer and target orbital plane, measured from center of target at the moment light seen at observation time leaves the target. Positive values indicate observer is above the objects' orbital plane, in the direction of reference-frame +z axis. Units: DEGREES 'Cnst' = Constellation ID; the 3-letter abbreviation for the name of the constellation containing the target centers' astrometric position, as defined by IAU (1930) boundary delineation. See documentation for list of abbreviations. 'TDB-UT' = Difference between the uniform Barycentric Dynamical time-scale and the Earth-rotation dependent Universal Time. Prior to 1962, the difference is with respect to UT1 (TDB-UT1) and the 0.002 second maximum amplitude distinction between TT and TDB is not maintained. For 1962 and later, the difference is with respect to UTC (TDB-UTC) and periodic terms less than 1.e-6 second are ignored. Values beyond the next July or January 1st may change if a leap-second is later required by the IERS. Values from the present date forward through the next ~78 days are predictions. Beyond that prediction interval, the last prediction is taken as a constant for all future dates. Units: SECONDS 'ObsEcLon ObsEcLat' = Observer-centered IAU76/80 ecliptic-of-date longitude and latitude of the target centers' apparent position, with light-time, gravitational deflection of light, and stellar aberrations. Units: DEGREES 'N.Pole-RA N.Pole-DC' = ICRF right ascension and declination of the target body's north-pole direction at the time light left the body to be observed at print time. Target pole/rotation model is given in the header. Units: DEGREES 'GlxLon GlxLat' = Observer-centered Galactic System II (post WW II) longitude and latitude of the target centers' apparent position, with light-time, gravitational deflection of light, and stellar aberrations. Units: DEGREES 'L_Ap_SOL_Time' = Local Apparent SOLAR Time for observing site. This is the time indicated by a sundial. TOPOCENTRIC ONLY. Units: HH MM SS.ffff (sexagesimal angular hours) '399_ins_LT' = Instantaneous light-time of the station with respect to Earth center at print-time. The geometric (or "true") separation of site and Earth center, divided by the speed of light. Units: MINUTES 'RA_3sigma DEC_3sigma' = Uncertainty in Right-Ascension and Declination. Output values are the formal +/- 3 standard-deviations (sigmas) around nominal position. Units: ARCSECONDS 'SMAA_3sig SMIA_3sig Theta Area_3sig' = Plane-of-sky (POS) error ellipse data. These quantities summarize the targets' 3-dimensional 3-standard-deviation formal uncertainty volume projected into a reference plane perpendicular to the observers' line-of-sight. SMAA_3sig = Angular width of the 3-sigma error ellipse semi-major axis in POS. Units: ARCSECONDS. SMIA_3sig = Angular width of the 3-sigma error ellipse semi-minor axis in POS. Units: ARCSECONDS. Theta = Orientation angle of the error ellipse in POS; the clockwise angle from the direction of increasing RA to the semi-major axis of the error ellipse, in the direction of increasing DEC. Units: DEGREES. +DEC ^ \ | theta\| +RA <----+----- |\ | \ Area_3sig = Area of sky enclosed by the 3-sigma error ellipse. Units: ARCSECONDS ^ 2. 'POS_3sigma' = The Root-Sum-of-Squares (RSS) of the 3-standard deviation plane-of-sky error ellipse major and minor semi-axes. This single pointing uncertainty number gives an angular distance (a circular radius) from the targets' nominal position in the sky that encompasses the error-ellipse. Units: ARCSECONDS. 'RNG_3sigma RNGRT_3sig' = Range and range rate (radial velocity) formal 3-standard-deviation uncertainties. Units: KM, KM/S 'DOP_S_3sig DOP_X_3sig RT_delay_3sig' = Doppler radar uncertainties at S-band (2380 MHz) and X-band (8560 MHz) frequencies, along with the round-trip (total) delay to first-order. Units: HERTZ and SECONDS 'Tru_Anom' = Apparent true anomaly angle of the targets' heliocentric orbit position; the angle in the targets' instantaneous orbit plane from the orbital periapse direction to the target, measured positively in the direction of motion. The position of the target is taken to be at the moment light seen by the observer at print-time would have left the center of the object. That is, the heliocentric position of the target used to compute the true anomaly is one down-leg light-time prior to the print-time. Units: DEGREES 'L_Ap_Hour_Ang' = Local apparent HOUR ANGLE of target at observing site. The angle between the observers' meridian plane, containing Earth's axis of-date and local zenith direction, and a great circle passing through Earth's axis-of-date and the targets' direction, measured westward from the zenith meridian to target meridian along the equator. Negative values are angular times UNTIL transit. Positive values are angular times SINCE transit. Exactly 24_hrs/360_degrees. EARTH TOPOCENTRIC ONLY. Units: sHH MM SS.fff (sexagesimal angular hours) 'phi PAB-LON PAB-LAT' = "phi" is the true PHASE ANGLE at the observers' location at print time. "PAB-LON" and "PAB-LAT" are the J2000 ecliptic longitude and latitude of the phase angle bisector direction; the outward directed angle bisecting the arc created by the apparent vector from Sun to target center and the astrometric vector from observer to target center. For an otherwise uniform ellipsoid, the time when its long-axis is perpendicular to the PAB direction approximately corresponds to lightcurve maximum (or maximum brightness) of the body. PAB is discussed in Harris et al., Icarus 57, 251-258 (1984). Units: DEGREES, DEGREES, DEGREES 'App_Lon_Sun' = The apparent target-centered longitude of the Sun ("apparent L_s") as seen at the target when the light recorded by the observer at print-time reflected off the target. It is referred to a coordinate system where the x-axis is the equinox direction defined by the targets' instantaneous IAU2015 pole direction and heliocentric orbit plane at reflection time, and is measured positively in an eastward direction (counter-clockwise around the positive pole of the solar system angular momentum vector). On bodies other than the Earth, the quantity can indicate boundary dates for the seasons: Northern hemisphere Southern hemisphere 0= Spring Equinox 0= Autumn Equinox 90= Summer Solstice 90= Winter Solstice 180= Autumn Equinox 180= Spring Equinox 270= Winter Solstice 270= Summer Solstice For Earth seasons, instead see quantity #31 ("ObsEcLon") as seen from the geocenter, with the Sun as a target. If the target has no associated spin-pole model (common for asteroids and comets), "n.a." will be output. Units: DEGREES 'RA_(ICRF-a-apparnt)_DEC' = Airless apparent right ascension and declination coordinates of the target in the ICRF reference frame, with down-leg light-time, gravitational deflection of light, and stellar aberration. Units: RA : HH MM SS.ff{ffff} (hours-minutes-seconds of time) DEC: DG MN SC.f{ffff} (degrees-minutes-seconds of arc) 'I_dRA*cosD I_d(DEC)/dt' = The angular rate of change in the targets' ICRF inertial reference-frame apparent RA and DEC, with light-time, gravitational light deflection, and stellar aberrations. d(RA)/dt is multiplied by the cosine of declination to provide a linear rate in the plane-of-sky. Units: ARCSECONDS PER HOUR 'Sky_motion Sky_mot_PA RelVel-ANG' = Total apparent angular rate of the target in the plane-of-sky. "Sky_mot_PA" is the position angle of the target's direction of motion in the plane-of-sky, measured counter-clockwise from the apparent of-date north pole direction. "RelVel-ANG" is the flight path angle of the target's relative motion with respect to the observer's line-of-sight, in the range [-90,+90], where positive values indicate motion away from the observer, negative values are toward the observer: -90 = target is moving directly toward the observer 0 = target is moving at right angles to the observer's line-of-sight +90 = target is moving directly away from the observer UNITS: ARCSECONDS/MINUTE, DEGREES, DEGREES 'Lun_Sky_Brt sky_SNR' = Sky brightness due to moonlight scattered by Earth's atmosphere at the target's position in the sky. "sky_SNR" is the visual signal-to-noise ratio (SNR) of the target's surface brightness relative to background sky. Output only for topocentric Earth observers when both the Moon and target are above the local horizon and the Sun is in astronomical twilight (or further) below the horizon, and the target is not the Moon or Sun. If all conditions are not met, "n.a." is output. Galactic brightness, local sky light-pollution and weather are NOT considered. Lunar opposition surge is considered. The value returned is accurate under ideal conditions at the approximately 8-23% level, so is a useful but not definitive value. If the target-body radius is also known, "sky_SNR" is output. This is the approximate visual signal-to-noise ratio of the target's brightness divided by lunar sky brightness. When sky_SNR < 1, the target is dimmer than the ideal moonlight-scattering background sky, so unlikely to be detectable at visual wavelengths. In practice, visibility requires sky_SNR > 1 and a detector sensitive enough to reach the target's magnitude, even if it isn't washed out by moonlight. When relating magnitudes and brightness values, keep in mind their logarithmic relationship m2-m1 = -2.5*log_10(b2/b1). UNITS: VISUAL MAGNITUDES / ARCSECOND^2, and unitless ratio 'UT1-UTC' = Difference between the UT1 and UTC timescales ("DUT1"). UT1 is the Earth-rotation dependent mean solar time on the Greenwich meridian sometimes referred to as GMT. UTC is a discontinuous timescale derived from the atomic TAI timescale, adjusted by leap seconds to provide a civil timescale maintained within 0.9 seconds of UT1. Therefore, the difference UT1-UTC will have discontinuities where leap-seconds are inserted in UTC. UTC is not well-defined prior to 1962, so "n.a." will be returned for earlier dates. The UT1 here is a JPL fit to measurements of the Earth rotation which can change rapidly and unpredictably at the 10^-4 second level due to tides and other factors affecting Earth rotation. Values for the 14 days prior to the present date are considered provisional and may change at up to the 0.002 second level as data accumulates, corresponding to about 1-meter (3-sigma) for an Earth equatorial site. Values from the present date forward through the next ~78 days are predictions. Beyond that prediction interval, the last prediction is taken as a constant for all future dates. Units: SECONDS Computations by ... Solar System Dynamics Group, Horizons On-Line Ephemeris System 4800 Oak Grove Drive, Jet Propulsion Laboratory Pasadena, CA 91109 USA General site: https://ssd.jpl.nasa.gov/ Mailing list: https://ssd.jpl.nasa.gov/email_list.html System news : https://ssd.jpl.nasa.gov/horizons/news.html User Guide : https://ssd.jpl.nasa.gov/horizons/manual.html Connect : browser https://ssd.jpl.nasa.gov/horizons/app.html#/x API https://ssd-api.jpl.nasa.gov/doc/horizons.html command-line telnet ssd.jpl.nasa.gov 6775 e-mail/batch https://ssd.jpl.nasa.gov/ftp/ssd/horizons_batch.txt scripts https://ssd.jpl.nasa.gov/ftp/ssd/SCRIPTS Inquiries : Jon.D.Giorgini@jpl.nasa.gov ******************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************** !$$SOF COMMAND = '499'